A virtual network element (Virtual Network Element, VNE) is a cluster router technology. Multiple routers in a two-layer or multi-layer convergence structure are virtualized and converged, based on software technologies, into a virtual convergence node, which is externally presented as a single-image cluster router. A control plane and a management plane of the VNE are integrated in a master router, that is, a master node. Another router functions as a standby node and other routers are slave nodes. All nodes within the VNE can perform traffic forwarding.
Within the VNE, generally routers that have a large capacity, a high performance, a high-performance central processing unit (Central Processing Unit, CPU), and a higher network position serve as a master node and a standby node. The master node collects an internal topology of the VNE, performs corresponding calculation to generate an internal Forwarding Information Base (iFIB), and then delivers the iFIB to other nodes to complete route calculation within the VNE. When a packet enters the VNE, the iFIB is queried first to obtain an outbound interface of the VNE and then the packet is forwarded to a corresponding VNE node; and then when the packet reaches the node where the outbound interface resides, an external Forwarding Information Base (eFIB) is queried to obtain a next hop and then the packet is forwarded from the VNE. In view of the whole forwarding process, the VNE externally shields internal interconnection details and is presented as a single-image super node, and from a perspective of an entire network topology, it is a route node that externally provides a unified eFIB for forwarding packets.
The VNE technology simplifies a network topology, improves route convergence and stability, and reduces management complexity. Compared with a multi-chassis router, the VNE does not require introducing a dedicated interconnection device or an interconnection interface technology. This protects the existing investment, saves investment, and reduces operation and maintenance costs. In addition, according to a network application, devices of different models and forms may be converged to reduce device maintainability.
An existing solution for calculating an internal topology within the VNE is an On Demand Routing (ODR) technology. However, the ODR technology has a small application scope, and is applicable only to a hub-spoke (hub & spoke) topology but not applicable to other topology structures such as a dual-homing tree and a ring.